Systems for dispensing a plurality of different fluids into a container have been known and used for many years. For example, systems for dispensing paint base materials and colorants into a paint container are known. These paint systems may use twenty or more different colorants to formulate a paint mixture. Each colorant is contained in a separate canister or package and may include its own dispensing pump. The colorants and the respective pumps may be disposed on a turntable, along one or more horizontal rows or through a dispense manifold that includes a plurality of nozzles. In a turntable system, the turntable is rotated so that the colorant to be dispensed is moved to a position above the container being filled. In designs using one or more horizontal rows, the container may be moved laterally to the appropriate colorant/pump. In manifold designs, the container or receptacle remains stationary as the colorants are sequentially or simultaneously pumped though individual nozzles held closely together by a manifold block.
Systems for dispensing large varieties of different fluids are not limited to paints, but also include systems for dispensing pharmaceutical products, hair dye formulas, cosmetics of all kinds, nail polish, etc. As noted above, some systems for use in preparing products at a point of sale may also use a stationary manifold through which a plurality of nozzles extend. Each fluid to be dispensed is then pumped through its own individual nozzle that is accommodated in the manifold. Depending upon the size of the container and the quantity of the fluids to be dispensed, manifolds can be designed in a space efficient manner so that a single manifold can accommodate twenty or more different nozzles. The nozzles are connected to the various ingredients by flexible hoses and the ingredients are contained in stationary canisters. Each canister may be associated with its own pump.
In many fluid dispensing applications, precision is essential, as many formulations require the addition of precise amounts of certain ingredients. This is true in the pharmaceutical industry but also in the paint and cosmetic industries as the addition of more or less tints or colorants can result in a visible change in the color of the resulting product.
One way in which the precision of dispensing systems is compromised is “dripping”. Specifically, a “leftover” drip may be hanging from a nozzle that was intended to be added to a previous formulation and, with a new container in place under the nozzle, the drop of liquid intended for a previous formulation may be erroneously added to a new formulation. Thus, the previous container may not receive the desired amount of the liquid ingredient and the next container may receive too much.
To solve the drip problem, various scraper and wiper designs have been proposed. However, these designs often require one or more different motors to operate the wiper element and are limited to use on dispensing systems where the nozzles are separated and not bundled together in a manifold. Use of a wiper or scraping function would not be practical in a multiple nozzle manifold design, as the ingredients from the different nozzles will be cross-contaminated by the wiper or scraper, which would then also contribute to the lack of precision of subsequently produced formulations.
Another problem associated with dispensing systems that make use of nozzles lies in the dispensing of relatively viscous liquids such as tints, colorants, base materials for paints and cosmetic products, certain pharmaceutical ingredients or other fluid materials having relatively high viscosities. Specifically, the viscous fluids have a tendency to dry and cake onto the end of the nozzles, thereby requiring frequent cleaning in order for the nozzles to operate effectively. For example, when a liquid or slurry material dries on a nozzle, the dispense stream may be misdirected causing the liquid or slurry to miss the receptacle. This problem is particularly prevalent in the dispensing of paint colorants or tints. While some mechanical wiping or scrapping devices are available, these devices are not practical for multiple nozzle manifold systems for the reasons set forth above and the scraper or wiper element must be manually cleaned anyway. Nozzles have also been known to clog entirely when exposed to air for an extended period.